1. Technical Field
Example embodiments of the present invention relate to systems for tracking the past and current locations of a person, who has a signal transmitter, such as a missing child or an abducted person using a signal transmitted by the signal transmitter held by the missing child or the abducted person, signal transmitters, sensor network gateways used in the same, and methods of tracking the location of the person having the signal transmitter.
2. Description of the Related Art
Kidnapping and abduction has caused social problems. Besides such crimes, many accidents such as missing child, disappearance have happened. Conventionally, there were methods of locating a mobile communication terminal held by a person using a Global Positioning System (GPS) for the purpose of locating abducted persons or missing children.
However, according to such methods, there is an assumption that abducted persons or missing children should always have a mobile communication terminal after they are abducted or lost, but, in actual situations, it is rarely possible for them to keep having the mobile communication terminal with themselves.
A recently developed method of locating an abducted person or a missing child using a short-range wireless communication technique is disclosed in Korean Patent No. 627655 (entitled as “Method of requesting SOS using a wireless ID and a data transmitting device). According to Korean Patent No. 627655, a person in an emergency situation must press a button for requesting SOS, but, in the real situations, there are many situations where it is hard for the person in the emergency situation to press the button—for example, a situation in which a child cannot press the button easily, a situation in which a person is abducted, tied up or fall unconscious abruptly, a situation in which a person is hit by a car in an instant—therefore, the method of locating an abducted person or a missing child according to Korean Patent No. 627655 cannot be used in practical situations.
Furthermore, according to Korean Patent No. 627655, it is impossible to acquire a location of an abducted person or a missing child when a mobile communication terminal of another person does not exist near the abducted person or the missing child in emergency situations.
Furthermore, according to Korean Registration Patent No. 627655, an SOS signal is simply transmitted to a central control office via mobile communication terminals of another person near a signal transmitter of the abducted person or the missing child, so that the method of Korean Patent No. 627655 cannot provide reliable and systematic protection of abducted persons or missing children.